multipath-tools: upgrade git rev

There is no new release for package multipath-tools. And just upgrade
its git rev to the latest commit 0.5.0-144-g770e6d0 on Feb 16, 2015.

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>